When displaying the lists, the device reads each book, renders the first page and uses that for the cover. So, how long displaying a page in the list takes depends on how long that takes. For books in the main memory, the rendered cover is saved on the device and reused each time it is needed. For books on the SD card, the cover is rendered each time it is needed.

So, the speed is probably a bit of both. The devices are very low powered and generating the covers is a fairly intensive action, so it will take time. And the actions for books on the SD card seem a bit slower than the main memory. Plus the above difference in how the device handles covers.

But, 50 seconds seems very long. I don't normally use an SD card in my Glo and I can't test it at the moment. But, I thought it was taking about 10 seconds to display the list the last time I had the card in.

Using caibre, I have side loaded over 50 epubs onto the Micro SD Card.

When I view the books, it takes about 3 to 5 seconds per book for the book covers to render. (Kobo shows 6 books per page, so it takes about 50 seconds to render one page of books)

It seems to load a little faster when I save the epub on the main device.

I don't know the slow rendering of book cover pages is due to the Micro SD or is it the Kobo software that cannot render the book cover pages fast enough.

What I've found is that the small block random read/write speed of the card seems to make more difference than the class which seems to be predicated on the large block read/write speeds. There are several sources for information on those parameters, check https://docs.google.com/spreadsheet/...E#gid=0http:// for one database of test results.

What it meant for me is that a 8GB Class 4 Sandisk gives me faster cover loading and book opening speeds than a 8GB Class 10 Patriot. Yes, the Patriot blows the Sandisk away on large blocks but the Sandisk is about 4x read and 10x write faster on small blocks using Crystal DiskMark and a Sandisk uSD/USB adapter.

I have the first Kobo, the one with the knob on the lower right. I have a 8 GB card with about 700 books loaded and it takes hours to process the content the first time I loaded the card. I'm going to have to delete a couple hundred and load more on the actual device to speed things up. I simply keep too much on the card even when I have space on the reader. I move books from the card to home and work computers.

I've upgraded internal memory from 4GB sandisk to cheap 32GB transcend class 4. Firmware version 2.6.1. So far this card is loaded about 7500 epubs. It was painfully slow powering Glo for the first time but defragmentation and second power up halped.